Device manufacturers are continually challenged to deliver value and convenience to consumers by, for example, providing integrated circuits that perform at optimal levels while occupying minimal space. Three-dimensional integrated circuits increase processing capabilities while reducing an overall footprint of the integrated circuit compared to a conventional two-dimensional integrated circuit having similar processing capabilities. Some three-dimensional integrated circuits, such as three-dimensional integrated circuits, include p-channel metal-oxide-semiconductor (PMOS) transistors and n-channel metal-oxide-semiconductor (NMOS) transistors. The PMOS transistors and NMOS transistors are sometimes formed on different wafers that together combine to form the three-dimensional integrated circuit.